Basalt

Definition

Basalt is a fine-grained, dark-colored volcanic rock that primarily consists of plagioclase and pyroxene minerals. It forms from the rapid cooling of lava that erupts onto the Earth's surface, making it one of the most common types of igneous rock found in the Earth's crust. Basalt plays a crucial role in the rock cycle as it can weather and alter to form soil or sediment, and it is also involved in processes that contribute to the formation of new geological features.

5 Must Know Facts For Your Next Test

1. Basalt is primarily formed at mid-ocean ridges, where tectonic plates diverge and magma rises to fill the gap.
2. As one of the most abundant rocks in the Earth's crust, basalt covers much of the ocean floor and many volcanic islands.
3. The rapid cooling process of basalt gives it a fine-grained texture, making it less porous than other igneous rocks like granite.
4. Basalt can transform into other rock types through weathering, erosion, and sedimentation processes within the rock cycle.
5. Some notable features formed from basalt include columnar jointing and basalt plateaus, which can be seen in places like the Giant's Causeway in Ireland.

Review Questions

• How does basalt form and what conditions are necessary for its formation?
  • Basalt forms from the rapid cooling of lava that erupts onto the Earth's surface during volcanic activity. The necessary conditions for its formation typically involve an eruption at mid-ocean ridges or hotspots where tectonic plates diverge or converge. The lava cools quickly upon contact with air or water, resulting in a fine-grained texture characteristic of basalt.
• Discuss the role of basalt within the rock cycle and how it interacts with other rock types.
  • Within the rock cycle, basalt plays a significant role as an igneous rock that can undergo various processes. Over time, basalt may weather and erode into smaller particles, contributing to sediment that can form sedimentary rocks. Additionally, under heat and pressure conditions, basalt can be transformed into metamorphic rocks. This interaction highlights how basalt contributes to both the formation and transformation of different rock types throughout geological processes.
• Evaluate the environmental implications of basalt formation at mid-ocean ridges and how this affects global geological activity.
  • The formation of basalt at mid-ocean ridges has significant environmental implications as it is associated with tectonic plate movements that lead to volcanic activity. This process not only contributes to the growth of oceanic crust but also influences marine ecosystems by releasing nutrients into ocean waters. Additionally, these geological activities can cause earthquakes, affecting coastal communities. The continual formation and recycling of basalt at these locations are essential for maintaining geological balance and biodiversity within marine environments.

Related terms

Igneous Rock: A type of rock that forms through the cooling and solidification of magma or lava.

Magma: A molten mixture of minerals, gases, and water found beneath the Earth's surface that can lead to volcanic eruptions when it rises to the surface.

Tectonic Plate: Massive slabs of Earth's lithosphere that move and interact with each other, causing geological phenomena like earthquakes and volcanic eruptions.